JPH04323722A - Drawing system for multiwindow system - Google Patents

Abstract

PURPOSE:To quickly draw a graphic and to prevent the errors of the graphic on division boundaries by using a graphic command generated by coordinate values after clipping processing to perform the drawing processing. CONSTITUTION:A graphic command generating means 21 generates the graphic command based on the drawing request from a user program 10, and a window clip list preserving means 22 divides the display face of a window into plural rectangles to preserve coordinate information when the display face of the window is not rectangular. A clipping position coordinate value calculating means 23 calculates the coordinate values of intersections between element segments of the graphic to be drawn and rectangles based on rectangle coordinate information preserved in the window clip list preserving means 22, and a graphic command reproducing means 24 uses the coordinate values of intersections calculated by the clipping position coordinate value calculating means 23 to generate a new command. A drawing means 25 performs the drawing processing based on this command generated by this means 24.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drawing method for a multi-window system.

0002

2. Description of the Related Art In general, a graphic processing system having a multi-window system can display a plurality of windows, so the windows may overlap. In such a case, since the lower window is hidden in the area where the windows overlap, it is necessary to perform clipping to prevent drawing of the figure located in that area. Clipping processing is performed using a rectangle as a clipping frame. Therefore, if a window partially overlaps with another window and the display surface of the window becomes a shape other than a rectangle, the display surface is divided into a plurality of rectangles, and clipping processing is performed for each divided rectangle. Next, by performing a drawing process on the figure portion located within each divided rectangle, the figure to be displayed becomes one continuous figure.

Conventionally, in the drawing method of this type of multi-window system, the drawing position is determined from the coordinate values, and each time one dot is drawn, the coordinate values of the clipping frame of the display area are used to locate the dot within the display area. It is determined whether the object is located within the display area, and drawing processing is performed if it is located within the display area. For example, when drawing a line segment from one vertex to the next, calculate the dot positions to be drawn between the vertices, and determine whether each dot position is within the clipping frame. ing.

0004

The drawing method of the conventional multi-window system described above has a problem in that the drawing speed is slow because it is determined whether the position of every dot is within the clipping frame.

The present invention has been made in view of these conventional problems, and it is an object of the present invention to provide a drawing method for a multi-window system that can perform clipping processing and drawing processing for a multi-window system at high speed. .

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a graphic command generating means for generating graphic commands based on a graphic drawing request from a user program, and a display surface of a window. is a shape other than a rectangle, the display screen is divided into multiple rectangles and the coordinate information of the divided parts is saved based on the clip list storage means of the window and the rectangular coordinate information stored in this clip list storage means. , a clipping position coordinate value calculation means that calculates the coordinate values of the intersection of the element line segment of the figure to be drawn and the rectangle, and a new command is generated using the coordinate values of the intersection calculated by this clipping position coordinate value calculation means. The graphic command regenerating means includes a graphic command regenerating means, and a drawing means performs a drawing process based on the commands generated by the graphic command regenerating means.

[0007]

[Operation] Since the present invention is configured as described above, when drawing is performed by dividing one graphic command into multiple areas because the windows overlap, the graphic generated using the coordinate values after clipping processing is Since the drawing process is performed using commands, there is no need to judge the position when drawing.
It is possible to draw at high speed and the figure does not become incorrect at the divided boundary.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention. In the figure, 10 is a user program;
Reference numeral 21 denotes a graphic command generation means for generating graphic commands based on a drawing request from the user program 10, and 22 a means for dividing the display surface into a plurality of rectangles when the display surface of the window is in a shape other than a rectangle. A clip list storage means for the window that saves the coordinate information of the rectangle created.
Reference numeral 23 denotes a clipping position coordinate value calculation means for calculating the coordinate values of the intersection of the element line of the figure to be drawn and the rectangle based on the rectangle coordinate information stored in the clip list storage means 22 of the window, and 24 the clipping position. Graphical command regeneration means that generates a new command using the coordinate values of the intersection points calculated by the coordinate value calculation means; 25 is a drawing means that performs drawing processing based on the commands generated by the graphical command regeneration means 24; 30 is a graphic display device.

[0010] The clipping position coordinate value calculation means 23 and the figure command regeneration means 24 determine the clipping process based on the clipping frame of the window's clip list storage means 22, and if the figure exceeds the frame, the Generate a graphics command that changes the coordinates of the part to coordinates that intersect with the clipping frame and does not display graphics in the area where the windows overlap.

Next, the operation when there is a request to draw a figure will be explained with reference to the flowchart shown in FIG. When there is a request to draw a figure, the figure command generation means 21
First, a graphic command having an operation code, the number of vertices, and coordinate value data is generated (process 201). When generating graphical commands here, the size and position of the window, or the positional relationship with other windows, etc., are not taken into consideration. When actually displaying a figure on the figure display device 30, the figure command generated by the figure command generation means 21 is regenerated using the display position information given by the window's clip list storage means 22, and the command is regenerated using the coordinates. The value is set on the graphic display device 30. The clipping frame information of the display area held by the window's clip list storage means 22 is a value regarding each rectangle when the display surface is divided into multiple rectangles when the display surface is in a shape other than a rectangle, and is used when regenerating a graphic command. repeats the process for all coordinate values by the number of divided rectangles (process 202).

Window clip list storage means 22
An example of rectangular coordinate information stored by is shown in FIG. Figure 3 (a
) is an example of dividing window 1 in the horizontal direction when windows 2 and 3 overlap. Coordinate information (AXm
in, AYmin), (AXmax, AYmax),...
is saved. As shown in processes 203 to 206, when clipping is performed at the maximum value of the Y coordinate of the clipping frame parallel to the X axis, Y
Find the coordinate value of the intersection of the maximum coordinate value plus 1 and the line segment, and use that value to generate a command (process 205)
. The reason why it is possible to limit clipping only to frames parallel to the X axis is because it is assumed that the window will be divided horizontally. As shown in figure (b), when the window is divided vertically, clipping processing is performed at the maximum value of the X coordinate of the clipping frames parallel to the Y axis, and
Find the coordinate value of the intersection of the axis maximum value plus 1 and the line segment. The following will explain the case of horizontal division as an example. In the case of vertical division, the X and Y coordinates in the explanation below are simply replaced, so the explanation will be omitted. The reason for finding the intersection point between the maximum Y coordinate value plus 1 and the line segment in step 205 is that when clipping is applied to each rectangle and a command with coordinate values within the rectangle is generated, depending on the drawing position of the figure, This is to prevent the coordinate values from becoming discontinuous at the boundaries where the window is divided into rectangles, causing dots to be displayed incorrectly.

FIG. 4 shows a case where the display becomes incorrect. When window 4 and window 5 overlap and a figure is drawn in window 4, window 4 is a rectangle D.
It is divided into rectangles E, and graphic commands are generated for each rectangle. When trying to draw a line segment from D1 to E1 in the figure, if you find the intersection between DYmin and the line segment for rectangle D, if multiple X coordinate values correspond to Y coordinate value DYmin, the midpoint will be used as the intersection point. Since the value of is taken, the coordinates of the intersection point D2 are determined, and a graphic command for drawing a line segment from D1 to the intersection point D2 in the rectangle D is generated. Next, by finding the intersection of EYmax and the line segment for the rectangle E, the coordinates of the intersection E2 are found, and for the rectangle E, a graphic command for drawing a line segment from the intersection E2 to E1 is generated.

When drawing is performed using the graphics commands generated in this manner, the line segments become discontinuous at the boundary dividing the window into two rectangles, as shown in FIG. To prevent incorrect display, when clipping is performed using the maximum Y-coordinate value of the clipping frame, the X-coordinate value of the intersection of the value plus 1 and the line segment is determined. The value obtained by adding 1 to the maximum Y coordinate value is the minimum Y coordinate value of the rectangular clipping frame located above the rectangle currently being processed when the window is divided into a plurality of rectangles. Therefore, the same X coordinate value as the X coordinate value found in the clipping process of the upper rectangle is found here. Add 1 from the slope of the line segment to the X coordinate value, or
Determine whether to subtract 1 or leave the value unchanged, and use it as the X coordinate value of the line segment within the rectangle currently being processed. Since a command is generated that sets the X-coordinate value to a value in the range of -1 to +1 of the X-coordinate value of the figure in the upper rectangle, the X-coordinate value will be discontinuous at the dividing boundary, as shown in Figure 5. No problems will occur.

After repeating the process as many times as there are divided rectangles and regenerating the graphic command, the graphic is displayed by the drawing means 25 (process 206).

The drawing means 25 determines dot positions to be drawn between the vertices from the coordinate values of the vertices of the generated command, sets the coordinate values in the graphic display device 30, and simply performs the drawing process.

[0017]

[Effects of the Invention] As explained above, according to the present invention,
When drawing by dividing one graphic command into multiple areas because the windows overlap, the drawing process is performed using the graphic command generated with the coordinate values after clipping processing, so the dot position may be incorrect when drawing. Since there is no need to judge whether or not the drawing is within the clipping frame, it is possible to draw at high speed, and there is an effect that the figure will not become invalid at the dividing boundary.

[Brief explanation of drawings]

[Fig. 1] Block diagram of one embodiment of the present invention

[Figure 2] Flowchart showing the processing procedure when there is a request to draw a figure

[FIG. 3(a)] An explanatory diagram showing position information in the window's clip list storage means

[FIG. 3(b)] Explanatory diagram showing position information in the clip list storage means of the window

[Figure 4] Explanatory diagram showing an example of window display

[Figure 5] Explanatory diagram showing an example of window display

[Explanation of symbols]

10 Graphic processing user program 21 Graphic command generation means 22 Window clip list storage means 23
Clipping position coordinate value calculation means 24
Graphic command regeneration means 25 Drawing means 30 Graphic display device

Claims (1)

[Claims] Claim 1: In a drawing method for a multi-window system, there is provided a graphic command generation means for generating a graphic command based on a graphic drawing request from a user program, and a display controller that generates a graphic command when the display surface of a window is in a shape other than a rectangle. A clip list storage means of the window that divides the surface into multiple rectangles and saves the coordinate information of the divisions, and element lines of the figure to be drawn and the rectangle coordinate information stored in this clip list storage means. a clipping position coordinate value calculation means for calculating the coordinate value of the intersection point with the rectangle; a graphic command regeneration means for generating a new command using the coordinate value of the intersection point calculated by the clipping position coordinate value calculation means; 1. A drawing method for a multi-window system, comprising a drawing means for performing drawing processing based on commands generated by a graphic command regeneration means.